Improvelyient in



,E. S. HOWLAND'.

DRESS FOR'ME'TALLIG GRINDING RINGS.

OFFronf l I, ,Imenovenient NaonEss' -toeMET Arno G INninem,-

- Specification forming part of Lettere'Fatent No; dated May 1 23, 1876 {application filedi i October25,l 87 5. J v J a To cllwhomttmay ca v Be it known that I, EDMUND SLHOWIlAND, of Batavia, Kane county, State of Illinois,

have invented new and useful Improvements e in Dress for MetallicGrinding-Rings, of which the following is affull description, reference being had to theaccompanying drawings,

whic'h- Figure l is a top or plan view, Fig. 2, a

, side elevation; Fig. 3,'cross-section on line as w ofFig. 1; and Fig. 4, a broken ing the lines of the drift. A r e The object of this invention is to overcome the difficulties whichhave heretofore existed in adjusting the feeding ridges or drift with the grinding surface or drift, so as to make the feeding and grinding :un'iform. Where the feed has a greater. capacity than the grinding-surface the mill isliable to clog, and much additional power is required to run the ring, and where the capacity of the grinding-surface exceeds that of the feeding the full ca-' pacity of the mill cannot be obtained, and the partly in the eye of the ring, and partly upon its face, with a steep or sharp curve, as shown in Fig. 3 in accelerating the travel of the grain between the rings, by increasing the tangent or making the draft stronger as soonas the grain is partially crushed; and in finishing the grinding under a still stronger draft at the outer edge of the face; and in making the second and third grinding-faces very shallow or fine, as shown at Figs. 1 and 2.

In the drawing, Arepresents the body of the grinding-ring; B, the eye or central opening'; 0, the holesfor attaching the rings to suitable backing-plates; a, the feeding-drifts; b, the grinding-drifts, which project partly into the feeding portion of the ring between the gathering-points a; c, the ridges projecting across the second and third grinding-faces; d, theshort ridges, projecting or running across the third grinding-face. 1, Fig. 4, represents section, show-- the feeding-drifts or portion of the ring; 2

and 3, the grinding-faces, having each differnt angles or tangents of the grinding-ridges, which change the draft.

The ring shown is a full-sized three-and-ahalfinch grinding-ring, which ishalf an inch'thick, and which is usually made of coldshortor white cast-iron, but may-be made of any suitable-metal. The ridges are made very short, so, as to leave the. space between vthem very shallow, as shown,fwith the exception of the feeding-drift a. By reason of the strong curve upon which the feeding-drifts a are placed 'no more grain'will be taken up than can readily pass between the grindingfaces, and while they have a sufficient space between them to'keepthe ringsfull they cannot overcrowd the grinding-surfaces.

By giving the grinding-ridges on the face 2 a little stronger draftfthan that given the feed, the grain will be taken from'the feedingridges, and carried away-a little faster than it would be if the line of draft was continued on the same tangent, and thus prevent clogging at this point; and where the grindingridges pass to'the face 3'the tangent is still further increased, so as to increase the draft andprevent clogging at this point. As shown,

the laces 1, 2, and 3 are nearly-"of equal width, but they may be varied, and each of them made wider or narrower, as desired. By this arrangement of v the feeding and grinding ridges a wide surface is obtained without the clogging of the wide surfaces heretofore used. -1 am aware that-this result has been attempted to be obtained'by making the grindingsurfaces curvilinear; but the difficulty with these is that if started at a sufficient angle to feed the rings properly, the draft at the outer edge becomes too strong, and throws the grain out without a proper finishing of the grinding; and also that rings have been made with a change in the tangent near the outer edge of .the face; but this change has uniformly been made to checkinstead of to accelerate the draft.

By my improvements I have-{after long experiments, succeeded in equalizing the angle of the tangent, so as to produce exactly corresponding changes in the draft to prevent clogging, and to dispose of; the grain as fast I as it enters between the rings, and by making grinding-surface upon three tangents, substantially as and for the purpose set forth.

2. The shallow spaces between the grind! ing-ridges in combination with the fine sharp as set forth.

ridges for preventing clogging, substantially EDMUND s; HOWLAND.

Witnesses:

E. A. WEST,

O. W. BOND. 

